1. Field of the Invention
Embodiments of the present invention generally relate to method for monitoring and calibrating temperature in semiconductor processing chambers. More particularly, embodiments of the present invention relate to method for non destructive temperature measurement of semiconductor processing chambers operating at low temperatures.
2. Description of the Related Art
Shrinking feature size in semiconductor devices greatly increases the need for precise processing, which usually requires precise and uniform temperature control in a semiconductor processing chamber during processing. Precise temperature measurement during processing is critical to the ultimate quality of finished device on a substrate being processed.
Numerous methods may be used to monitor chamber temperature during processing depending on temperature and other parameters in a processing chamber during processing. Since a large portion of semiconductor processes are conducted in controlled environment, such as a vacuum environment, which is very sensitive to contamination, non-destructive temperature measurement methods, which do not interfere with processes performed in the processing chamber, are typically preferred.
Optical pyrometry, which samples and analyzes emitted thermal radiation from target objects, is one of the non-contact temperature measurement method often used in the state of the art processing chambers. Optical pyrometers may be positioned outside a processing chamber without contamination, interruption or interference with processing. However, optical pyrometry is limited to high temperatures, i.e. above about 500° C. because objects, such as semiconductor substrates, typically do not emit sufficient amounts of thermal radiation below 500° C.
For processing chambers configured to operate at temperatures below 500° C., no effective non-destructive temperature measurement method is available in the state of the art semiconductor processing.
Therefore, there is a need for apparatus and method for non-destructive temperature measurement effective at low temperatures.